1. Field of the Invention
The present invention relates to a localized plasmon resonance sensing device and a system thereof; in particular, it relates to a self-referencing localized plasmon resonance sensing device and a system thereof.
2. Description of the Related Art
The electron cloud on the surface of metal nanoparticles can be excited by an electromagnetic field of a specific frequency, which is resonant with the collective oscillation of the conduction electrons confined within the volume of the nanoparticles, accordingly also known as the Localized Plasmon Resonance (LPR), as shown in FIG. 1. The noble metal nanoparticle 1 generates an intense absorption band in the absorption spectrum, which is referred as the localized plasmon resonance band. The fundamental principle of the localized plasmon resonance sensing system is that, upon conjugation of a recognition unit on the surface of noble metal nanoparticle 1 and a target binds with the recognition unit, the target accordingly covers the vicinity of the surface on the noble metal nanoparticle 1, such that a change occurs in the surrounding dielectric environment at which the noble metal nanoparticle 1 is located and whose peak wavelength position and absorption are extremely sensitive to variation in the dielectric constant of the exterior surrounding, thus leading to alternation in the LPR resonance band; and finally by means of modifying the recognition unit for enabling specific detection capability, then through analysis on the relationship between the variation in the frequency or absorption of the resonance band and the concentration of the target, it is possible to establish a quantitative detection method. The method basically comprises modifying the noble metal nanoparticles on an optical waveguide, thereby forming a noble metal nanoparticle layer thereon. The said noble metal nanoparticle layer is made by one of the sphere-shaped noble metal nanoparticle, the cube-shaped noble metal nanoparticle, the prism-shaped noble metal nanoparticle, the rod-shaped noble metal nanoparticle and the shell-shaped noble metal nanoparticle, with essentially no connections existing between the nanoparticles, and the noble metal may be gold, silver or platinum. By using the effect of multiple total internal reflections along an optical waveguide, it is possible to accumulate the amount of change in the absorption of the evanescent wave due to absorption by the nanoparticle plasmon resonance so as to enhance the LPR signal for sensing operations. Meanwhile, through modification of the surface of the noble metal nanoparticle 1 with various recognition units, the functionalized noble metal nanoparticles can be applied to detection of various targets.
The single fiber-optic LPR sensing system lacks the ability to compensate influences caused by instrumental or environmental factors, such as baseline drift due to instability of the light source, and changes in the temperature or the composition of the solution to be tested, since the LPR sensing technology employs the sensitivity of the noble metal nanoparticle to the refractive index in the surrounding environment as a way to detect biological molecules, which is also dependent on the temperature or the composition of the samples. During detection of real samples, it is commonly required to control the temperature of the sample or undergo dilution more than two times in the sample preparation processes. An addition of temperature control system may increase system complexity while multiple dilutions may undesirably degrade the effective detection limit.